Internal links are hyperlinks on one web page that link to another resource or page on the same website. This structure allows them to pass SEO value or PageRank equity throughout the domain because visitors have more accessibility to valuable information. In other words, if you reference your own website sub-pages on your own website, then you are showing your readers that you have more useful information for them to digest. This keeps them on-site for longer, reducing your bounce rate and showing Google which if your pages are important.